1. Field of the Invention
The present invention relates to Impatiens plants having a bicolor petal pattern that is stable from flower to flower and is inherited in a predictable manner. In particular, this invention is directed to Impatiens wallerana exhibiting the novel stardust trait. The present invention also is directed to methods for introgressing the gene that controls the stardust trait into a variety of genetic backgrounds. The present invention is further directed to methods for testing whether a particular Impatiens plant carries the stardust gene.
2. Background
Impatiens is primarily an Old World genus of flowering plants, with species distributed throughout tropical Africa, India, South-West Asia, southern China, Japan, and spreading into the north temperate zones of Europe, Russia, China and North America. In general, see Grey-Wilson, IMPATIENS OF AFRICA (A. A. Balkema 1980), and Nehrling et al., THE PICTURE BOOK OF ANNUALS (Hearthside Press, Inc. 1966). The family Balsaminaceae contains the monotypic Hydrocera and the prolific Impatiens, commonly referred to as the Balsams. Balsams are among the most decorative plants in cultivation. Moreover, most of the species are easily grown and can flower over a long period. The Balsam family includes three species grown as annuals in gardens: I. balsamina, I. hawkerii, and I. wallerana.
I. wallerana is an extremely variable species with a wide distribution in central east Africa. This species has also migrated into or naturalized in many of the moist tropical areas of the world. I. wallerana is probably the most commonly grown species of Impatiens and is cultivated in many parts of the world. In the trade, I. wallerana is frequently referred to as I. sultani or I. holstii, and may be commonly called "Busy Lizzy," "Patient Lucy," "Patience Plant," or "Sultana."
I. wallerana characteristically has two-flowered inflorescences and bright green, somewhat translucent leaves. The inflorescence may occasionally be one-flowered or three-flowered, and sometimes as many as five-flowered. The usual two-flowered structure shows a reduction in that there are frequently several tiny additional bracts, or even aborted buds, above the uppermost flowers. In the one-flowered form, there are always additional bracts.
The flowers of I. wallerana are typically rather flat, with a large upper (dorsal) petal and lateral petals almost equal in size and shape that are fused together at the base. The species can be obtained in a variety of colors ranging from pink to orange, red, mauve, purple and white.
Two well-known color patterns in I. wallerana have been designated as "star" and "picotee." The star trait is characterized by a white strip that runs down each petal, while petals with the picotee pattern have a basic color with margins of a second color. Since these traits are polygenic, it is difficult to transfer the star or picotee pattern into other genetic backgrounds. In attempts to merge these traits with other desirable polygenic characteristics, the color pattern is often lost or diluted. Accordingly, multiple complex crosses are necessary to improve other polygenic traits. The result is that commercial picotee and star hybrids often have persistent habit, seed quality or other performance problems.
Therefore, a need exists for a means to control Impatiens flower color in a predictable manner within a variety of desirable genetic backgrounds.